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Correct resitance values for a rewound stator?

  • Thread starter Thread starter tfb
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tfb

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Evenin' all,

Have just had an enjoyable time rewinding a GS stator -- and no I'm not being sarcastic! Followed the directions via the GSR Garage and BWRinger's website that I'd printed off a while back. All good.

Got a question, though. Found a figure of 0.65 Ohms quoted in my old Haynes manual, as the correct resistance between each of the three phases (measured from the ends of the output wires that head off to the reg/rect.).

Using my multimeter I am getting 0.3 Ohms. Is this OK?

Thanks,
Mike.
 
I don't know the answer but might pm Steve he does this and sells them, should be able to give you an answer.
 
The resistance you measure will be directly related to the gauge of the wire and how many feet of it were wound into the stator.

I just measured one of my rewound stators, it was 0.8 ohms. Larger wire and fewer turns could easily give you lower numbers.

I think it is more important that all three legs read pretty much the same. If two legs were 0.7 and one was 0.3, I would be concerned, but if all of them are 0.3, you might be OK.

Another thing to consider is the accuracy of your meter. It is a bit unusual to get lower readings at really low values like that. It is more common to see about an ohm higher. Check your "zero" point by crossing your leads. Many meters will show 0.3 or so, which is the resistance of the meter leads themselves. If that is what you read with just your leads AND with your stator, you definitely have problems.

.
 
Steve said:
The resistance you measure will be directly related to the gauge of the wire and how many feet of it were wound into the stator.

I just measured one of my rewound stators, it was 0.8 ohms. Larger wire and fewer turns could easily give you lower numbers.

I think it is more important that all three legs read pretty much the same. If two legs were 0.7 and one was 0.3, I would be concerned, but if all of them are 0.3, you might be OK.

Another thing to consider is the accuracy of your meter. It is a bit unusual to get lower readings at really low values like that. It is more common to see about an ohm higher. Check your "zero" point by crossing your leads. Many meters will show 0.3 or so, which is the resistance of the meter leads themselves. If that is what you read with just your leads AND with your stator, you definitely have problems.

.
Click to expand...


Agreed on all points. Check again with a different/better meter and/or a fresh battery in your meter. Resistance readings are subject to measurement errors.
 
Thanks gentlemen!
Yes, I rewound the stator with a slightly thicker wire: 17AWG instead of the standard 18AWG. I got 21 winds on per pole, which was the number of winds that were already there.
Thanks for the tip re. zero-ing the multimeter -- will do.
I was under the impression that using a slightly thicker wire gauge than the standard (for our GS stators) would give the alternator a bit more "oompfh" (I think that's a technamickle lekky term :-P)... or is it that the extra winds of narrower wire would do that? Are there any trade-offs with thicker wire? Does voltage output go down while watts go up?
You can tell I'm a lekky noob, thanks for your patience.
Mike.
 
Thicker wire would certainly lead to lower resistance readings, so perhaps that explains things.

As I understand it (and I'll admit I'm not 100% certain on this) the amount of current you'll get is related by the number of turns of wire on each pole. If it's the same number, then you should get similar voltage readings.

High-output stators stuff in extra turns of wire on each pole one way or another. You can do this by using slightly thinner wire, thinner insulation, winding tighter or more efficiently, or just winding more wire if there's room. Thinner wire and denser windings can lead to problems with increased heat buildup, so it's always a tradeoff.
 
Thanks for that, bwringer (great website you've got, BTW). I guess the only way to see what voltage the thing choofs out is to install it. But as it's a spare item for when the next stator drops off the perch, that (hopefully) will be some time. :-)
Bat on,
Mike.
 
As Bwinger described there are several trade offs and it is not clear at all exactly how to wind for more turns and make it fit without comprising resistance. But there is one minor point to keep in mind; the max output power of the charging system is limited to the magnetic strength of your rotor. Do any gains or looses from how the stator is wound only has effect below the maximum which is typically achieved by 3.5-4k rpm.

this is the main reason as Steve described earlier the resistance can have a wide range. Even symmetry is strictly not nesessary but it is typically indicative of a winding issue so worth checking.
 
Trade-offs? Yeah, there are trade-offs.

Simple physics will tell you that more turns on the poles will give you more voltage. That will basically start giving you 'charging' voltage at, or just above, idle speed, but that just means that the (stock, shunt) R/R will start regulating (wasting) sooner.

Thicker wire will allow fewer turns on the poles, meaning that you might not see 'charging' voltage until slightly higher in the rev range.

Thinner wire has more resistance for a given length. Since it allows more turns (longer length), there is even more resistance.

Thicker wire has less resistance and allows more current to flow. If you want to add accessories (heated grips, heated clothing, extra lights, etc.), this might be the way to go.

.
 
Steve the electro sport stators are supposed to be wound for 20% more something.have you ever investigated that? I can't say I have measured the difference although I run them. If true it should boost the idle voltage without having to boost idle speed.
 
I got 21 winds on per pole, which was the number of winds that were already there.
Click to expand...
Yours might be a different stator than mine.or had been rewound once already? I counted about 30 when I rewound mine and with thicker wire I only got 24 back on and yes; a lower output voltage.

but Installing it will be the best test. My Battery is still in good condition a year later with a max output of 13.5 but I don't have a lot of stuff on at stoplights...if you gofor handwarmers and all that you might want a bigger battery.
 
Gorminrider said:
Yours might be a different stator than mine.or had been rewound once already? I counted about 30 when I rewound mine and with thicker wire I only got 24 back on and yes; a lower output voltage.

but Installing it will be the best test. My Battery is still in good condition a year later with a max output of 13.5 but I don't have a lot of stuff on at stoplights...if you gofor handwarmers and all that you might want a bigger battery.
Click to expand...
You got lower voltage at just idle or all RPMs?
 
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